Hearing aid



FIG. 1 is a front elevational view of a hearing aid, showing our new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof;

FIG. 7 is a front perspective view thereof, the broken line showing of the earplug is for illustrative purposes only and forms no part of the claimed design; and,

FIG. 8 is a cross-sectional view taken along line 8--8 of FIG. 7. 

The ornamental design for a hearing aid, as shown and described. 